On Natural Motions Caused by Gravity

...circular, such as those described by cord-pendulums. In the aforementioned rotational motion, the ascent of the less heavy part B through the arc BF is just as necessary and natural as the fall and descent of the entire weight through the arc DE to the lowest point E.

Although the ascent of part B is commonly thought to be a violent motion In the physics of this period, "violent motion" referred to any movement forced against an object's natural tendency, such as a heavy object moving upward., it is actually natural. If we consider the rotation and the proper placement of a heavy body, we see this motion is produced by a natural impulse. It is impossible for the body to reach its proper position without part B rising.

There is a logical rule: whoever intends an end must also intend the means necessary to reach that end. Therefore, we can reasonably infer that a natural force truly pushes the less heavy part upward toward F. We must admit that the ascent through BF is entirely natural. We might also say that the "violence" of this upward motion is included within the natural operation itself. Regardless, it is enough for us that this operation is necessary. It is impossible for it to happen any other way. Others may call it natural or violent as they wish.

PROPOSITION II.

Furthermore, it is not always necessary for two bodies to be placed at the ends of a balance original: "libræ," referring to a weighing scale or balance beam. for heavy bodies...